1. Field of the Invention
This invention relates to a blow-molded heat and pressure resistant bottle-shaped container made of biaxially oriented synthetic resin and, more particularly, to the construction of a heat and pressure resistant bottle-shaped container having a semispherical convex bottom for enhancing the pressure resistance thereof and a base cap securely attached to said bottom for providing support for the container.
2. Prior Art
A wide variety of bottle-shaped containers made of biaxially oriented synthetic resin have been popularly used as containers for aerated or carbonated drinks. Particularly, bottles made of biaxially oriented polyethylene terephthalate resin are popular because of their excellent properties such as pressure resistance.
In order to obtain a high pressure resistant bottle requiring less synthetic resin molding material, a bottle having a semispherical bottom has been used. As apparent from the construction of the bottom of the bottle, the bottle is not selfstanding. Thus, a base cap of cylindrical shape for providing a support for the spherical bottom of the container has been associated fixedly with the bottom of the bottle to form the bottle-shaped container.
The bottle-shaped container of this type has been imparted with heat resistance by means such as heat setting to achieve sufficient heat resistance against heat at the time of filling the bottle with the content liquid.
When filling the bottle-shaped container with carbonated drink mixed with fruit juice and/or milk as well as other ingredients in the form of mixtures (hereinafter simply referred to as "mixed carbonated drinks"), the container is sealed, and then showered by or bathed in hot water for a predetermined period of time for sterilization by heat.
In order to introduce hot water into a space between the semispherically shaped bottom and the base cap so that an outer surface of the bottom of the bottle covered by the base cap can come into direct contact with hot water and consequently the process of heating and sterilization can be carried out surely and effectively, water inlets are formed. Since a great number of bottles are heated and sterilized, hot water is usually supplied to the bottles in shower state. Thus, said water inlets are normally realized in the form of many gaps arranged between an open end of the base cap and the outer surface of the bottle so that such gaps offer ease of introducing the hot water running from above along the outer surface of the bottle-shaped container into the space.
The above described arrangement of providing water inlets in the form of many gaps between the base cap and the outer surface of the body of the bottle is advantageous because the hot water supplied in the shower state runs down along the outer surface of the body of the bottle and goes into the space between the bottom of the container and the base cap through the water inlets surely and smoothly, and such water inlets can be formed very easily.
A bottle-shaped container of this type is attached around the body with a shrunk label which is made of heat-shrinking synthetic resin film for the purpose of protecting the contained mixed carbonated drink, indicating the content of the bottle and decorating the appearance of the container. This container is provided with ridges integrally formed with the bottle on the outer surface of its body for preventing the shrunk label from slipping out. One of the ridges is formed at the lower end of the body or at the boundary between the body and the bottom of the bottle and therefore located immediately above the gaps between the outer surface of the bottle and the base cap.
When the ridge is located immediately above the gaps as described above, the hot water running down along the outer surface of the bottle is inevitably moved radially as it passes over the ridge and can hardly go into the gaps located immediately therebelow so that consequently the bottom of the bottle may not be sufficiently heated.
Particularly, when the slipping out of the shrunk label is prevented by a shoulder with a reduced diameter and a ridge formed at the lower end of the body, the lower end of the shrunk label that surrounds the body reaches beyond the ridge and blocks the gaps of water inlets. Thus, the operation for applying and attaching the shrunk label to the bottle-shaped container has to be conducted not by the container manufacturer but by the drink producer after sterilization of the liquid content. Therefore, not only an increased number of operational steps but also installation of additional equipment for applying and bonding shrunk labels are necessary for the drink producer so as to push up the cost of the bottled final products.